A high pressure discharge lamp, such as a metal halide, mercury or high pressure sodium lamp, is typically powered by an electromagnetic ballast circuit incorporating an iron core. The electromagnetic ballast arrangement receives voltage from a power source, and outputs a ballast voltage for driving the lamp. The ballast circuit, which uses the iron core to achieve the necessary voltage adjustment, represents a major component of ballast cost, as well as bulk. The foregoing type of ballast circuit typically suffers the problem of powering only a single high pressure lamp. Existing solutions to more efficiently utilizing a ballast circuit so that it simultaneously powers plural (e.g. dual) high pressure gas discharge lamps sometimes suffer difficulties in starting a wide range of lamps available from various manufacturers. Another problem has been that high pressure discharge lamps undergo physical changes that alter their starting characteristics as they age causing similar difficulties in starting. It would be desirable to utilize a ballast transformer so that it powers plural high pressure discharge lamps, and realizes a considerably reduced per-lamp ballast cost and improved ballast efficiency, while minimizing the above mentioned starting difficulties.